From: Robert Klemme <bob.news@...>
Date: 2004-12-09T21:47:28+09:00
Subject: Re: Inheritance, mixins and initializers


"Robert Klemme" <bob.news@gmx.net> schrieb im Newsbeitrag
news:31qukrF3d6rb9U1@individual.net...
>
> "Johan Nilsson" <johan.nilsson@---.esrange.ssc.se> schrieb im
Newsbeitrag
> news:1102594375.344eddcc1c357ac539046c764cd8c6b8@teranews...
> > Hi,
> >
> > I've got a question regarding inheritance, mixins, order of
> initialization
> > and calling module/super class "initializers". I'd like to do
something
> > along the lines of (pseudo-ruby code):

<snip/>

Here's another solution - even more general:

class Foo;end
class Bar;end
class Baz;end

module FieldMixin
  def fields(*classes)
    classes.each do |cl|
      attr_reader cl.name.downcase.to_sym
    end

    define_method(:initialize) do
      super()
      classes.each do |cl|
        instance_variable_set( "@#{cl.name.downcase}", cl.new )
      end
    end
  end

  def inherited(cl) cl.extend FieldMixin end
end

class Base
  extend FieldMixin
end

class Derived < Base
  fields Foo, Bar
end

class Der2 < Derived
  fields Baz
end

Derived.new.foo
Derived.new.bar
Der2.new.foo
Der2.new.baz

Kind regards

    robert